Solo Select

Coat Color Genetics

Horse Coat Color Calculator

Cross two horses and predict foal coat color probabilities.

Sire

Color-only input infers the possible genotypes and weights them equally. Switch to By genotype if you have test results.

Dam

Color-only input infers the possible genotypes and weights them equally. Switch to By genotype if you have test results.

Foal color probabilities

  • Bay32.8%
  • Buckskin32.8%
  • Chestnut12.5%
  • Palomino12.5%
  • Black4.7%
  • Smoky Black4.7%

Assumptions from color-only input

  • Extension could be E/E or E/e, a black-based coat hides which, so both are enumerated.
  • A bay can be A/A or A/a, both are enumerated.
  • Agouti is invisible on a red (chestnut-based) coat, so A/A, A/a and a/a are all possible.
  • Palomino is one cream on a red base (N/Cr).

What this tool does

Cross a stallion and a mare and see the probability of every foal coat color. It models the genes that matter in Quarter Horse and western performance programs: the red/black base (extension and agouti), the dilutions that define ranch and cow-horse color, cream, dun, champagne, pearl and silver, and the modifiers gray and roan. It also carries a required safety check: a clear warning when a cross risks a frame overo lethal white foal.

Enter known genotypes for an exact answer, or enter what each horse looks like and the tool infers the possibilities and shows its assumptions. It is a genetics predictor, not a DNA test, and not a substitute for one.

How to use it

  1. Enter the sire. Pick the stallion's coat color, or switch to 'By genotype' and set each gene from his test results.
  2. Enter the dam. Do the same for the mare.
  3. Read the odds. The calculator lists every possible foal color with its probability and a color swatch, and warns about frame overo lethal white risk.
  4. Open the genetics detail. Toggle the genetics detail to see the reasoning, blue-eyed double dilutes, gray masking, and the assumptions behind color-only input.

The genetics behind it

Every horse carries two alleles at each color gene and passes one at random to each foal. The base coat comes from two genes: extension (MC1R) decides red versus black pigment (ee is chestnut), and agouti (ASIP) decides how black pigment is arranged, A_ restricts it to the points for bay, aa leaves a uniform black. Agouti is invisible on a red horse but is still passed on, which is why a chestnut can throw a bay foal.

Dilutions lighten that base. One cream makes palomino, buckskin or smoky black; two makes the pale, blue-eyed cremello, perlino and smoky cream. Dun adds a dorsal stripe and gives red dun, dun and grulla. Champagne, pearl and silver each shift color in their own way, silver only touches black pigment, so it hides on a red horse. Gray is progressive and masks everything over time, and roan mixes white hairs through the coat.

A note on the color swatches

The page uses only the brand’s maroon, black and white, except the coat swatches themselves, which show real horse colors because that is the information the tool exists to convey. Swatches are approximate; every horse varies.

Frame overo and lethal white

This is the one outcome that is a welfare issue, not just a color. Frame overo (EDNRB) is recessive for its lethal effect: a single copy is a healthy, frame-patterned horse, but a foal with two copies is born all white and dies within days from an unformed colon. Two frame carriers have a 25% chance of producing such a foal. Any horse with unexplained white body spotting, including minimally marked solids, should be tested for frame before it is bred to another possible carrier.

Frequently asked questions

How does a horse coat color calculator work?

It applies Mendelian inheritance to each color gene independently. For every locus, extension (red/black), agouti, cream, dun, champagne, silver, gray, roan and frame, each parent passes one of its two alleles at random. The calculator combines the per-gene odds into a probability for every possible foal color.

Can I use it if I only know the horse's color, not its genotype?

Yes. Choose 'By color' and pick the visible coat. The tool enumerates every genotype that can produce that color and weights them equally, because without a test or the horse's own parents there is no way to know which is more likely. It shows those assumptions with the result. For an exact answer, test the horse and switch to 'By genotype'.

What is a frame overo lethal white foal, and why does the calculator warn about it?

Frame overo is caused by the EDNRB gene. A horse with one copy (N/O) is a healthy frame-patterned horse, but a foal with two copies (O/O) is born all white and dies within days from an unformed colon (intestinal aganglionosis). Breeding two frame carriers gives a 25% chance of this outcome, so the calculator flags it prominently. Test both horses for frame before breeding.

Why can two chestnut horses never have a bay or black foal?

Chestnut is genetically ee at the extension gene, it has no black-based pigment to pass on. Two ee parents can only pass e, so every foal is ee (red-based). Dilutions and white patterns can still vary, but the base stays red.

How does gray work in the calculator?

Gray is dominant and progressive, a gray horse is born colored and lightens with age, masking whatever is underneath. The calculator shows a gray outcome while keeping the underlying base color in the detail, because that hidden color is exactly what gets passed to foals.

Is this the same as a DNA test?

No. This predicts probabilities from the genetics you enter; it does not test any horse. For breeding decisions, order a coat color panel from an accredited lab such as the UC Davis Veterinary Genetics Laboratory, Etalon, or Animal Genetics, then enter the confirmed genotypes here.

Sources

The inheritance model traces to the UC Davis Veterinary Genetics Laboratory and the peer-reviewed literature:

Related: the Quarter Horse genetic health panel checker and the foaling date calculator.